1. Field of the Invention
The present invention relates to an insulative oxide porcelain composition used for, for example, ceramic multilayer substrates and ceramic electronic components.
2. Description of the Related Art
Hitherto, an oxide porcelain composition composed of BaO—Al2O3—SiO2 is known as an insulative material used for ceramic multilayer substrates and ceramic electronic components. For instance, Japanese Unexamined Patent Application Publication No. 4-16551 discloses a porcelain composition containing oxides of Si, Ba, Al, B, Cr and Ca. This oxide porcelain composition can be fired at a low temperature and over a wide temperature range. Furthermore, this oxide porcelain composition has a high insulation resistance and a small relative dielectric constant.
Meanwhile, electrical circuit devices including those containing a ceramic multilayer substrate or a ceramic electronic component are being reduced in size. Accordingly, reducing the size and the layer thickness of ceramic multilayer substrates and ceramic electronic components is desired. Therefore, an oxide porcelain composition having a flexural strength that can meet size-reduction requirements is desired.
In general, the flexural strength of a ceramic significantly depends on its composition. A substrate composed of the porcelain composition disclosed in the above patent application has a flexural strength of less than 200 MPa. As a result, cracks may be generated when such a substrate is mounted on an electrical circuit device. Thus, the known porcelain composition cannot satisfactorily meet the market's requirements.